This application claims the benefit of Korean Patent Application No. 10-2004-0088916, filed on Nov. 3, 2004, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.
1. Field of the Disclosure
The present disclosure relates to a non-volatile memory device using carbon nanotubes (CNTs) as charge transport channels and comprising a memory cell having a molecular adsorption layer.
2. Description of the Related Art
A memory device includes a memory cell for writing and reading information and a transistor for switching an electrical current flow during writing and reading of the information in the memory cell.
CNTs have excellent electrical conductivity and thermal stability and may have a long length of the order of micrometers with a diameter ranging from several nanometers to several tens of nanometers. CNTs may be applied to nano electro mechanical system (NEMS) devices having microstructures. Extensive research has been conducted on the use of CNTs in various devices and they are now used in electric field emission devices, optical switches in the field of optical communication, biodevices, etc.
Methods of manufacturing CNTs are well known in the art. Examples include arc discharge, pulsed laser vaporization, chemical vapor deposition, screen printing, spin coating.
To use CNTs in a memory device, p-type and n-type transistors are required. However, conventional transistors using CNTs exhibit ambipolar properties in a specific atmosphere or vacuum. Such transistors having ambipolar properties cannot be used as electronic devices.
A method of converting an ambipolar carbon nanotube field effect transistor (CNT FET) into a unipolar CNT FET is described in NANO LETTERS, 2004 Vol. 4, No. 5, PP 947-950. In this method, a gate oxide layer on a drain electrode side was etched and a portion of a silicon substrate below the etched region was “V” cut to realize a p-type CNT FET. However, the process of obtaining the unipolar CNT FET is very complex.
Thus, there is a need to readily produce a p-type transistor using a CNT as a channel region.